Whilst looking up something, I stumbled upon the following links that you may find useful. Several are from the Royal Horticultural website, plus some others:

Specifically on spuds
http://www.rhs.org.uk/plants/documents/ ... tato04.pdf

Other RHS reports:
http://www.rhs.org.uk/plants/plant_trials.asp

Looked interesting, esp if you live near Kent
http://www.thepotatoshop.com/index.html

A bit detailed, but if you're after something specific (like drought resistance, or Cooking type), just click on the characteristic, then click on the item you want on the next page and it will show you the varieties:
http://www.europotato.org/characterindex.php

Direct lookup of specific varieties:
http://www.europotato.org/varietyindex. ... ?page_no=1

Enjoy, Colin